The present invention relates in general to resistive switching devices (RSDs). More specifically, the present invention relates to fabrication methodologies and resulting structures for forming protuberant contacts that communicatively couple an RSD to a conductive row/column electrode line of a crossbar array without degrading RSD performance.
Resistive random access memory (RRAM) is a nano-scale non-volatile memory (NVM). RRAM provides simple storage cell components, high density, low power, large endurance, fast write, read and erase speeds, and excellent scalability. A typical RRAM storage cell is two-terminal device formed as a metal-insulator-metal (MIM) structure. The insulator material can be a binary metal oxide, which makes the MIM storage cell compatible with silicon-based CMOS (complementary metal oxide semiconductor) fabrication process. When a sufficient electrical signal is applied across the metal electrodes of a MIM, the resistance of the insulator can be switched from one resistance state to another. The insulator retains its current resistance state until an appropriate electrical signal is applied across the metal electrodes to change it.
RRAM, along with the logic circuitry used to address, read and write individual RRAM cells, can be implemented in a crossbar array, which is compatible with a variety of electronic circuits and devices, including neuromorphic architectures. A basic crossbar array includes a set of conductive row electrode lines and a set of conductive column electrode lines formed to intersect the set of conductive row electrode lines. The intersections between the two sets of electrode lines are separated by a so-called “cross-point” device, which, in memory circuits, can be implemented as an RSD.